Few Irish towns have colder winter nights than Oldcastle
Peak summer warmth arrives in July, with afternoons near 19.5°C. Expect the heaviest rain in December and the lightest in May. Its July afternoons stay fresher than in 82% of Irish towns. The frost-free window for a garden runs roughly 22 April to 23 October.
Met Éireann 1991–2020 averages for the town’s own square kilometre.
A year in Oldcastle at a glance
Each month’s typical high and low, in °C.
What stands out about Oldcastle’s climate
Compared with Irish towns, with its place among towns of 2,500+ in County Meath beside it.
What a year in Oldcastle feels like
Typical highs and lows by season and by month, from Met Éireann’s 1991–2020 averages.
43 frosts and 2 days of 25°C a year
Ground frosts, when the grass drops below 0°C, come on about 107 nights a year. Air frosts come mostly from October to April, most of all in January (about 9).
Air frosts by month
Average nights below 0°C
Ground frosts by month
Average nights with the grass below 0°C
Counted from Mullingar’s daily readings, 1991–2020, 29 km south-west of Oldcastle: Met Éireann publishes these for its stations only. At that distance, read them as the area’s climate.
About 1,022 mm of rain a year
December is the wettest month and May the driest. The wettest of 13 towns of 2,500+ in County Meath. The wettest month brings about 1.6 times the rain of the driest. Mullingar records 1 mm or more on about 165 days a year, and 10 mm on about 25.
Rain by month
Millimetres
Heating a home in Oldcastle
83% of a year’s heating need falls between October and April. Months averaging under 10°C: October to April.
Degree days add up how far each day’s mean temperature falls below 15.5°C over a year.
Living with Oldcastle’s climate
What the averages mean for a garden, a free afternoon and a bad-weather day.
In half of years the last air frost at Mullingar comes by 22 April and the first by 23 October: about 184 frost-free days in between.
Highs of 17–27°C with lows of 8°C or more: Jun, Jul, Aug and Sep.
Parks & trails →Averages smooth over storms, floods and heatwaves; Oldcastle’s hazards page covers the risks.
Flood & hazards →Met Éireann’s nearest station: Mullingar
Mullingar is 29 km south-west of Oldcastle, the nearest of the 25 synoptic stations where Met Éireann records the weather around the clock. The station stands 101 m above sea level; Oldcastle’s centre, 106 m.
| Month | High | Low | Rain | Air frosts |
|---|---|---|---|---|
| January | 7.6°C | 1.8°C | 91 mm | 8.7 |
| February | 8.3°C | 1.7°C | 77 mm | 8.7 |
| March | 10.1°C | 2.4°C | 69 mm | 7.2 |
| April | 12.6°C | 3.8°C | 70 mm | 3.0 |
| May | 15.3°C | 6.3°C | 66 mm | 0.4 |
| June | 17.8°C | 8.9°C | 75 mm | 0.0 |
| July | 19.2°C | 10.8°C | 80 mm | 0.0 |
| August | 18.9°C | 10.4°C | 85 mm | 0.0 |
| September | 16.9°C | 8.5°C | 76 mm | 0.1 |
| October | 13.4°C | 6.0°C | 99 mm | 1.8 |
| November | 10.0°C | 3.5°C | 99 mm | 5.2 |
| December | 7.8°C | 2.0°C | 100 mm | 8.2 |
| Year | 13.2°C | 5.5°C | 986 mm | 43 |
The table is Mullingar’s own record, averaged over 1991–2020 from its daily readings (ours, not a Met Éireann table). The temperatures and rain elsewhere on this page are Met Éireann’s 1 km grid at Oldcastle itself; the frosts and degree days are this station’s.
How Oldcastle compares
Against the 321 Irish towns and city neighbourhoods of 2,500 or more, each read from Met Éireann’s grid at its own centre, and its place among towns of 2,500+ in County Meath.
Warmer than it used to be
Oldcastle’s 1991–2020 average is 0.3°C warmer than 1981–2010’s. The biggest change is in February (+0.4°C).
A year’s rain is 1,022 mm, up 3% from 988 mm.
Change by month
The two periods share 1991–2010, so the gap is a decade’s step, not the change between two separate 30-year periods.
Oldcastle and its neighbours
Every town next door is within half a degree of Oldcastle in January and July. Choose a measure to recolour the map; tap a town for its climate.
The towns next door, side by side
The nearest towns of 1,000+ within 19 km: a hill, a valley or the sea can make a real difference over a short distance.
| Town | July high | January low | Rain a year |
|---|---|---|---|
| Oldcastle | 19.5°C | 1.7°C | 1,022 mm |
| Virginia 8.9 km | 19.5°C about the same | 1.7°C about the same | 1,043 mm |
| Ballyjamesduff 11 km | 19.4°C about the same | 1.7°C about the same | 1,080 mm |
| Castlepollard 13 km | 19.6°C about the same | 1.8°C about the same | 990 mm |
| Mullagh 15 km | 19.5°C about the same | 1.6°C about the same | 1,004 mm |
| Kells 19 km | 19.7°C about the same | 1.8°C about the same | 931 mm |
Each town’s colour is Met Éireann’s 1 km grid at its own centre, so towns a few kilometres apart can differ.
Oldcastle weather by month
Average daily high and low, mean temperature and rain, 1991–2020, for the town itself (Met Éireann’s 1 km grid).
| Month | High | Low | Mean | Rain |
|---|---|---|---|---|
| January | 7.6°C | 1.7°C | 4.7°C | 96 mm |
| February | 8.3°C | 1.6°C | 5.0°C | 80 mm |
| March | 10.2°C | 2.5°C | 6.3°C | 72 mm |
| April | 12.8°C | 4.0°C | 8.4°C | 70 mm |
| May | 15.6°C | 6.5°C | 11.1°C | 65 mm |
| June | 18.1°C | 9.2°C | 13.7°C | 76 mm |
| July | 19.5°C | 11.1°C | 15.3°C | 85 mm |
| August | 19.1°C | 10.9°C | 15.0°C | 91 mm |
| September | 17.0°C | 8.9°C | 12.9°C | 77 mm |
| October | 13.4°C | 6.2°C | 9.8°C | 103 mm |
| November | 10.0°C | 3.6°C | 6.8°C | 103 mm |
| December | 7.8°C | 1.9°C | 4.9°C | 105 mm |
| Year | 13.3°C | 5.7°C | 9.5°C | 1,022 mm |
How much a month can swing
December swings the most: over 30 years its average ranged from −1.1°C (2010) to 7.4°C (2015). September is the most reliable, staying within 3.6°C.
Where Oldcastle’s numbers come from
Averages over 30 years, not a forecast: the town’s own from Met Éireann’s grid, the frosts and degree days from its nearest station.
- Temperature and rain: Met Éireann’s 1991–2020 averages on its 1 km grid (Climatological Notes 22 and 23), read at the grid point nearest Oldcastle’s population centre (0.6 km away).
- Weather station: the nearest of Met Éireann’s 25 synoptic stations, Mullingar, 29 km south-west, from Met Éireann’s station list.
- Frosts and degree days: Mullingar’s daily readings from Met Éireann (clidata.met.ie), 1991–2020, averaged by month: a month counts when 27 or more of its days were read (rain and sunshine: every day), and a figure needs 10 such years.
- Then and now: Met Éireann’s 1981–2010 averages on the same 1 km grid, at the same point.
- Altitudes: the town’s ground from the Copernicus GLO-30 surface model (a few metres high in built-up places), the station’s from Met Éireann.
- Comparisons: every Irish town and city neighbourhood of 2,500 or more, read the same way; the five city totals are left out.
- Not on this page: sunshine at this station, snow and wind. Met Éireann publishes none of them on a grid; the frosts here are its nearest station’s, not the town’s own.
Met Éireann 30-year averages · Met Éireann open data. Under Creative Commons Attribution 4.0 (CC BY 4.0).
Questions about Oldcastle’s climate
How warm does Oldcastle get in summer?
July is the warmest month, with average highs of 19.5°C.
How cold does Oldcastle get in winter?
The coldest nights come in February, averaging 1.6°C. At Mullingar, the nearest Met Éireann station, the air drops below 0°C on about 43 nights a year (1991–2020).
How much rain does Oldcastle get?
About 1,022 mm a year, more than 59% of Irish towns. December is the wettest month (105 mm) and May the driest (65 mm).
How sunny is it?
Met Éireann publishes its 1991–2020 sunshine averages for its weather stations only, not on the 1 km grid this page reads, so there is no sunshine figure for Oldcastle itself. Its nearest synoptic station is Mullingar.
Are these figures for Oldcastle itself?
Partly. The temperatures and rain are Met Éireann’s 1991–2020 averages on its 1 km grid, read at Oldcastle’s population centre; the frosts, degree days and year-to-year swings are those of Mullingar, 29 km south-west, the nearest of its synoptic stations.
Where do these figures come from?
Met Éireann’s 1991–2020 climate averages, published as maps of Ireland in 1 km squares (Climatological Notes 22 and 23); the page reads the square at Oldcastle’s population centre. They are 30-year averages, not a forecast.
Copyright Met Éireann. Source: www.met.ie. This data is published under a Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Met Éireann does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use. This material has been modified from the original: TownRatings reads the 1 km grid at each town’s population centre. Today’s forecast for Oldcastle →
Contains Central Statistics Office (CSO) data, Census 2022, and Tailte Éireann boundaries (CSO Urban Areas, Small Areas, local electoral areas, constituencies), under Creative Commons Attribution 4.0 (CC BY 4.0).